Viking is a free/open source program to manage GPS data. You can import, plot and create tracks, routes and waypoints, show OSM, Bing Aerial and other maps, geotag images, see real-time GPS position (not in Windows), make maps using Mapnik (not in Windows), control items, etc.
It is written in mostly in C (with some C++) & the GTK+2 toolkit.

The SourceForge OpenRasMol project is an adjunct to the RasMol and OpenrasMol project at http://rasmol.org. It is hoped that the SourceForge OpenRasMol project will provide a convenient focal point for active collaborative contributions.

Fldigi is a modem program for most of the digital modes used by radio amateurs today: CW, PSK, MFSK, RTTY, Hell, DominoEX, Olivia, and Throb are all supported. It can help calibrate a sound card to a time signal and do frequency measurement tests.

Bot Sentry is a Pidgin (libpurple) plugin to prevent Instant Message (IM) spam. It allows you to ignore IMs unless the sender is in your Buddy List, the sender is in your Allow List, or the sender correctly answers a question you have predefined.

An original bruteforce-based encryption/decryption system. BBE was originally conceived to chat with encrypted text on IRC. mIRC and X-Chat support BBE via script addon. BBE can also encrypt MIME encoded files. Blowfish encryption is currently supported.

This tutorial demonstrates how easy it is to accomplish real world programming goals with Rebol. The text aims to teach average users to program computers to do useful things, without the long and difficult learning curve imposed by other languages.

EOS is a library that allows automated XML marshalling/demarshalling of Pascal Business Objects and complex object structures and it's easy linking to the GUI through the ModelBridge framework. You can use it with Delphi, Kylix and Free Pascal.

MoioSMS is a Python script to send messages from Internet sites. It supports Windows, Linux and Mac OS X, with both GUIs ad command line interfaces. MoioSMS features a plugin-like architecture that allows to add sites and UIs easily.

Baker is a cross platform (Linux/Mac/Windows) Rsync GUI frontend written in C++ and Qt4 to backup or restore multiple file and folders with features such automatic poweroff computer, mail alerts and for executing jobs before and after each transfer.